Welding process



Pinned Feb. 6, i940 2,189,595

UNITED. "STATES" PATENT OFFICE ww I "f a i the" no imam in, so, 1031,

- serial No. 143,125 l p 1 Claim. (CL 219-10) This invention relates tothe deposition of molvided a suitable source of alternating or directten metal by fusion-deposition welding methods. electric current; meansfor varying and control- In many fusion-deposition welding processes,ling the current, for example, a variable resistincluding particularlythe deposition of hard, ance or reactance; and suitable leads for con- 5wear-resistant metal from a welding rod onto a nectlng the currentsource to the portion of the 5 softer, tougher metal article-anbperationcomarticle to be heated. The temperature of the mcnly called "hardsurfacing" it is'necessary to article may be, controlled by the amountof curpreheat the article to be surfaced and to mainrent used, and thehard surfacing operation may tain it at a relatively high temperaturethroughbe carried on while the current is flowing. thus out the entireoperation in order to prevent insuring the maintenance of asubstantially uni-.10

stresses which would cause the article to crack. form temperature in thearticle throughout the Sometimes, the article to be surfaced is heatedto Operation. reby eliminatin he e ood of the desired temperatureinafurnace, and then stresses occurring therein.

. removed from the furnace and hard surfaced in In order to render allparts accessible, the

the open air, This procedure has all the disacb article may be rotatablymounted, and if it is 15 vantages inherent in every intermittent heatingdesired to heat only certain portions of the arprocess. The articlebegins to cool immediately ticle, t is may read y b wwmphshed by 0011-upon its removal from the furnace, and may have I neeting. the current.supp y leads Only to the r to be reheated many times before thehardsurspecified area. v

facing can be completed. The method wastes I'hewe1d1ng or hard-surfacingmetal may be :0 't l b and mu t provide unjfom applied to;the surface ofthe heated article by .body temperature during hard surfacing. fusingand depositing metal from a metal weld- Another procedure for hardsurfacing coming rod in an electric are or an oxyacetylene or prisesbuilding a furnace around the articleto o e high temperature flame. Inmany l u besurfgced and welding within t furnace, 1 stances it ispreferable intermittently to heat and 1 though this method avoids someof the disadreheat the article or part after such article or vantages ofthe previously described method, it part has'been raised to the desiredhard Surfac- ,1 no means perfect. The furnace is usually ing temperatureand during the deposition there crude, wastes heat, and, fails toprovide uniform on of the molten hard surfacine m l, T y 80 heating. Thewelder is-exposed to excessive heat, be accomp s ed e er byl manualcontrol 01 y so and it is diflicult and often impossible to reach all nautomatic mechanism for p ic lly t rnin of the parts to be hard surfacedor otherwise the heating current on for 5 15 Se d then welded, v v offfor 15 seconds, and so on until the operation Objects .of this:invention are t provide an has been completed. Intermittent applicationof 86 improved welding process, for instance a process the heltingCurrent n this manner is' advan- 5 for hard surfacing' metal articles,which process Z because the herd Surfacins tal Often is free from thedisadvantages of the methods s app successivelyv to comparatively s allheretofore used; to provide and continuously areas of the surface of theheatedartlcle. The maintain a substantially uniform high tempera-"localized heat of the are or the heating flame .40 ture in the, .articlethroughout the welding opthat melts the-hard surfacing rod tal, as well40 eration; to render all parts of theheated article t molten metal.heat-S Such areas to a conaccessible for hardsurfacing or welding; toavoid siderably higher mperature than the rest of the subjecting thewelder toexcessive heat; and to P being hard surfaced; and que tly theallow the heating of only those parts of an article temperatures ofcertain portions of the article which it is desired to weld or hardsurface. will differ. An intermittent flow of heatin Cur- 4s Theseandother objects are accomplished, acrent through the article tends tomaintain a cording to this invention, by electrically heating moreexactly uniform temperature throughout the metal articles, or partsthereof, independently the article than 'a continuously flowing current,of the welding heat. In heating by this method, since it is necessary insome instances to cut off an electric current of sufficient strength toraise the continuously flowing current at either fre- 50 the temperatureof thearticle to the .desired dequent or infrequent periods to balancethe added gree by resistance or ohmic heating may be heat derived fromthe hard facing flame or are passed through the article or'portlo'nthereof to and then reheat the article again as soon as the' be weldedor hard surfaced. average temperature drops due to the heat dissi- M Inapplying the invention, there should be prorated from e article whilethe current is u A specific example of a successful application of theinvention will serve to illustrate the meth od more clearly. Acrankshaft, of-which the main and crank bearings were to be surfacedwith a wear-resistant alloy of the cobalt-chromium-tungsten type, wasconnected to the two terminals of a transformer. A current of about 6700amperes was passed through the shaft, at

a voltage between 3 and 10 volts, whereby them temperature of the shaftwas raised to between about 700 F. and 900 F. and maintained at asubstantially uniform temperature during the,

hard surfacing operation. An wry-acetylene flame was thereupon appliedto a welding rod comprising an alloy of the cobalt-chromiumtungstentype, the rod was-fused, and the molten metal was deposited, in theusualmanner of welding, on successive portionscof the so-heated hearings tocomplete the hard surfacing operation.

This invention is especially advantageous for hard surfacing articles,such as shafts, bearings, die blocks, and cutting blades, whichare'subject to considerable wear; but it will be evident that theprinciples disclosed are of general application in, depositing metal ona metal worl piece which is heated electrically andonto which the weldmetal is fusion deposited by a high temperature heating mediumindependent of the means for electrically heating the workpiece.'

\ article.

And while the method of electrically heating the workpiece has beendescribed with particular reference toheating by ohmic heating, it isevident that it is possible and often advantageous to a heat thearticle-by induction or high frequency electrical methods.-

a What is claimed is:

- Process of hard surfacing a metal articlewhichcomprises passingarr-intermittently interrupted heating current of a periodicity of about15 sechard surfacing metal of the cobalt-chromiumtungsten type and to arelatively small portion only of the surface of said article; meltinga.por-- tion of said rod by means of said flame, and;de-,

positing said melted .portion of rod on said portion of thesurfaceofs'aid article; and continu ing the passing of saidintermittently interrupted l0 'onds through saidarticle said currentbeing of sufficient magnitude to raise the temperature of' the articleto a preheat temperature between 'about"700 F.,and 900 F.; applying ahigh temperature gas flame to a welding rod composed of,

electric current through. the articleduring the deposition of molten rodmetal whereby the heat intermittently applied to said article bysaidelectric current and the heat applied by the gas flame is allowed todistribute itself throughout the article to substantially uniformlyheat, the

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